On the advanced tab there's a setting 'avoid crossing outline for travel movements. This also has a detour factor. In itself this works, however, if the detourfactor is reached, it'll plot a direct route. One can't completely make travel movements voids objects on the plate.
However, in some cases, this is exactly what one wants. For instance, when printing the 3dlabprint airplanes, these are single-walled prints which are slightly overextruded. The result is that during these prints, it happens that the nozzle slightly hits a wall during a travel movement.
It would be nice to have an extra setting 'z-hop for travel movements'. This could be added on the advanced page. I'd make it so that you can set 'avoid crossing outline', then the detourfactor and then a checkbox 'use z-hop if avoiding is not possible'.